Fast Charging Algorithm Based on Electrochemical Model Suppressing Battery Degradation

Abstract

The charging speed of Lithium-ion batteries is one of the critical factors for the convenience of electric vehicles and mobile electronic devices. However, there is always a trade-off between charging speed and battery health. Simply increasing charging speed without considering the internal states of the battery results in lifespan and safety problems. Therefore, the challenging issues of developing fast charging algorithm are not only to increase the charging speed but also to minimize deterioration of the battery cells.In this work, we developed fast charging algorithm that optimizes the charging current profile based on electrochemical thermal (ECT) model. The goal of the optimization is to minimize degradation rate of the battery at a given charging time. In addition, the fast charging algorithm was designed to update the optimal charging current profile as the battery deteriorates.We developed the algorithm that automatically updates the aging parameters of the ECT model as the battery deteriorates. The ECT model is implemented on a multi-stage constant current charging (MSCC) method controlled by anode potential. In order to find the optimal charging current profile, the optimization algorithm was developed that minimizes the degradation rate. We defined the ratio of the increase in the charging time to the decrease in the amount of deterioration as the objective function. Through iterative process of changing the anode potential, the optimization algorithm searched a maximum value of objective function at a given charging time. In addition, as the battery deteriorates, the optimal charging current profile was continuously updated to minimize the degradation rate. Experimental results have shown that proposed charging algorithm can reduce the charging time and degradation rate compared with voltage-controlled MSCC method.